When to accept?

I got in with tier 3 AES (should be getting more than that, but that's for later), and I was wondering when I should accept the offer? I am not 100% certain I am going yet as my other colleges have yet to let me know (the latest being February). I should be getting priority housing/parking, so would I miss out on those if I'm a little late or anything? I just want to be able to wait long enough where I have all my college decisions and I can make a choice. Any insight is appreciated.